1. Field of the Invention
The present invention relates to an apparatus, method, and computer program for analyzing image data. More specifically, the present invention relates to an apparatus, method, and computer program for performing image analysis that allows a user to view correctly a time-division stereoscopic image.
The present invention also relates to an apparatus, method, and computer program for generating a control signal for an image display control process or other control process. In the image display control process, appropriate image displaying is performed by determining whether each frame is a left image or a right image in time-division stereoscopic image data containing no information indicating whether each frame thereof is a left image or a right image, and in the other control process, observation eyeglasses for viewing the display image and a polarizer are controlled.
2. Description of the Related Art
Image data of video media, such as television and video apparatus, is typically displayed on a flat screen. A person viewing the displayed video may not perceive depth information related to the video. It is well known in the art that the stereoscopic displaying technique allows a viewer to perceive a depth even if the image data is displayed on a flat surface. The stereoscopic displaying technique, though in a practical use phase thereof, has not been widely accepted.
A three-dimensional (3D) television receiver supporting stereoscopic viewing is now commercially available, and testing of stereoscopic image broadcasting on a general broadcasting network has started. Cinemas showing a 3D movie are rapidly increasing. An environment of enjoying the 3D video is thus going to be established.
In the stereoscopic displaying, videos captured from different viewpoints are presented to the left and right eyes of the viewer so that the viewer may perceive a depth because of parallax between the left and right images or because of convergence. As a result, humans can perceive a depth even on the video data that is displayed on a flat surface. For example, Japanese Unexamined Patent Application Publication Nos. 9-107562, 8-30806, 10-51812, 2000-209614, 2005-151534, and 6-194602 disclose stereoscopic image display processes in the related art.
Various techniques of stereoscopic displaying presenting different videos on the left and right eyes have been proposed. One technique is a time-division method. In the time-division method, the different videos presented to the left and right eyes are alternately displayed (hereinafter a video to be presented to the left eye only is referred to as a left image and a video to be presented to the right eye only is referred to as a right image). For example, the left image is displayed as an even-numbered frame and the right image is displayed as an odd-numbered frame.
The viewer views the image with liquid-crystal shutter eyeglasses on. The liquid-crystal shutter eyeglasses alternately open and close the left and right eye sections thereof. At the presentation timing of the left image, the left eye section of the liquid-crystal shutter eyeglasses is opened and the right eye section is closed. This control causes incident light to the right eye of the viewer to be blocked while allowing the incident light to enter the left eye only. At the presentation timing of the right image, the right eye section of the liquid-crystal shutter eyeglasses is opened and the left eye section is closed. This control causes incident light to the left eye of the viewer to be blocked while allowing the incident light to enter the right eye only. The viewer thus views the left image with the left eye and the right image with the right eye. The stereoscopic image displaying is thus achieved.
In another technique, the left image and the right image are respectively displayed as a left-handed circularly polarized image and a right-handed circularly polarized image. The viewer wears polarized glasses, thereby alternately viewing the left image and the right image with the left eye and the right eye, respectively.
The liquid-crystal shutter eyeglasses and polarized glasses are known and used as a stereoscopic image display device of time-division type. When the liquid-crystal shutter eyeglasses are used in the stereoscopic image display system of time-division type, appropriate stereoscopic displaying may not be achieved if the opening timing of the liquid-crystal shutter eyeglasses is not synchronized with the display timing of the left and right images. More specifically, if left and right images are inverted, for example, the right eye section of the liquid-crystal shutter eyeglasses is opened with the left image presented, or the left eye section of the liquid-crystal shutter eyeglasses is opened with the right image presented, the viewer views a video with the depth thereof also inverted. The viewer thus perceives an object more behind than the right position thereof or more front than the right position thereof. As a result, the viewer may feel uncomfortable and even fatigued.
To avoid left-right image inversion, Japanese Unexamined Patent Application Publication No. 05-14932 discloses a stereoscopic television signal processing method. According to the disclosure, a left and right identification signal is superimposed on an image signal and shutter eyeglasses are driven in response to the identification signal. This technique still has to superimpose beforehand the left and right identification signal onto the image signal and does not work with time-division stereoscopic display image data if no identification information is superimposed on the image signal.
Also available is a driving device of shutter eyeglasses which includes a switch, with which the viewer can reverse the display timing of the left and right images if the viewer feels the image is left-right reversed. However, not all the viewers can properly recognize the occurrence of a left-right reverse image. It is not certain that a left image reliably alternates with a right image. A plurality of different pieces of image data are successively reproduced, the display timing of the left and right images is not necessarily consistent. The switching operation has to be performed each time the left-right image reversal takes place.